This is St Thomas's way of saying that God
governs according to general laws of nature and
thought. -- The following argument may be added
from Sum. Theol., 1a, q. 22, art. 2: "Since every
agent acts for an end, the direction of effects to an
end on the part of the prime agent extends wide as
His causality extends. Whenever in the workings of
an active cause anything occurs that is not directed
to an end, it is because that effect ensues upon the
working of some other cause beside the intention of
the original agent. But the causality of God, the
prime agent, extends to all beings: . . . hence all
things, whatsoever in any way have being, are
ordained by God to an end."